Preheat the oven to 180°C fan/200°C/gas mark 6.
To make the shortbread base, beat together the stork block and sugar until pale and smooth.
Then fold in the flour little by little until it comes together and forms a ball.
Roll the shortbread out and press into a lined loose bottom 8 inch square tin. Prick the base with a fork.
Bake in oven for 15 minutes. Once baked, allow to cool in the tin.
Meanwhile, to make the caramel, place all the ingredients in a pan and bring to the boil slowly. This will take 5-10 minutes and thecaramel should be amber and thick.
Pour the caramel over the top of the shortbread and place in the fridge for at least 2 hours to set.
For the chocolate layer, melt the chocolate in a bowl over a pan of simmering water.
Pour the melted chocolate on top of the set caramel layer and place back in the fridge to set for 1 hour.
Remove from the tin, and slice using a hot sharp knife to get a clean cut.